10-01-14

VCAP-DTA Objective 1.1 – Deploy Highly Available View Installations

So the first objective in the exam blueprint is “Deploy highly available View installations”. That can come in many forms. Looking at the main bullet points and the reference sources cited by VMware Education, let’s drill down into it.

  • Configure highly available connectivity to the View environment. So what we can we read into this objective? The reference source is the View Architecture Planning guide and the View Installation guide. My inference here is that we’re not going to be expected to manipulate any kind of load balancing or content acceleration product, and there’s no reason why we should as it’s not a core part of Horizon View.
    • Firstly we can ensure we reduce the single points of failure. We may be asked to add more Connection Servers if there are only individual instances. Remember to select Replica Server when being asked what type of Connection Server we wish to add. Only the first instance of a Connection Server in a replicated/ADAM group is the Standard View Connection server. Remember this, or you’re going to have problem adding servers to an existing group.
    • What else? Well there are the main features of vSphere such as DRS and HA which we can leverage to ensure that View Connection Servers not only come back up in the event of host failure, but also ensure the Connection Server has enough grunt to perform when lots of connections will be coming in. I don’t think it outlandish that we may be asked to configure a memory reservation for Connection Servers, after all, they’re Java based services remember and VMware’s best practice is to set a memory reservation on VMs hosting JVMs.
  • Configure stateful and stateless load balancing for a View implementation. What did we just say earlier, we shouldn’t be asked to configure a load balancing solution because it’s not part of Horizon View? I’m really not sure why this objective is listed in the blueprint. I’ve had a good look through the reference sources and there is nothing specifically listed there regarding stateful/stateless load balancing. I looked around for a good reference on this topic, and found a useful article at F5 which actually mentions View as well. However, some good things to remember :-
    • Stateless means the connection is not tied to an individual Connection Server or Pod on connection/reconnection. This can be referred to as persistence or some load balancers call this “stickiness”. No history of the previous connection is retained on the load balancer.
    • Stateful load balancers “distribute traffic based on L3,L4 or L7 criteria to increase traffic capacity and reliability by improving application performance”.
    • One caveat to the above is that I’m absolutely not a networking or F5 expert, so take the above with a grain of salt. If anyone can provide a better explanation, I’d be happy to amend this bit. To be honest, I’m not really sure what this has to do with core Horizon View apart from the behaviour on disconnect (logoff, retain session etc.)
  •  Implement vSphere cluster isolation and High Availability rules.  Now we’re back in the land where we know what we’re doing (or at least I do!). So as I mentioned earlier, one area you can look at in the area of highly available View infastructure components is to use vSphere High Availability to ensure a high level of resilience and availability for your Connection, Security and/or Transfer Servers.

    • Cluster isolation  – what you you want to do if a host becomes isolated? The safe option is the default option of leave VMs powered on, but the exam may ask you to adopt a more aggressive stance. Bit dangerous that one, you may end up restarting a Connection Server chock full of users that can communicate on the network quite happily.
    • VM Restart Policy – This setting will give you ability to override the cluster level setting which is usually “medium” for all VMs. In this particular case, it’s likely you’ll have to set rules to ensure Connection/Security/Transfer servers restart first before other VMs such as desktops, remember the dependencies here. In which case, don’t overlook vCenter Server and also SQL Server, if you have that virtualised. You’ll need to group those into the first VM restarts too.
  • Configure a View implementation with multiple vCenter Servers. As discussed in the previous blog posting, VMware will likely use this exam to reinforce the Pod and Block reference design, so to scale your View implementation into the thousands, you need to create blocks of 2,000 desktops with their own vCenter and manage them as one. This way you don’t kill a single vCenter with lots of power management requests (power off/on/, reboot etc) as well as pool provisioning tasks.
    • View Administrator is the web based administration tool used to connect vCenter servers into View.
    • Go to View Configuration | Servers | vCenter Servers | Add and fill out the relevant details for the vCenter Server you wish to add. Note also this is where you configure View Composer settings. You may not be asked to configure this first up, but worth remembering this is where to go when dealing with the Composer based questions.
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